The embodiments described herein relate generally to bearings, and more specifically, to a retainer for a rolling element bearing.
Bearing assemblies are utilized to permit the relative motion of one machine component or assembly with respect to another machine component or assembly. The bearing assembly typically has a first bearing component, for example an inner ring, that is fixed to a first machine component and a second component, for example an outer ring that is fixed to a second machine component. The first bearing component is permitted to have relative motion, typically to rotate, relative to the second bearing component.
Many bearing assembly applications provide for the rotation of the inner element which is secured to a shaft while the outer element is secured to a housing. Typically, the inner element rotates, but many applications provide for the outer element rotating and the inner element stationary.
Often the bearing assembly is mounted in a housing and the inner element which is secured to a shaft. The housing may be in the form of a housing with a mounting arrangement for mounting to a surface with fasteners.
The rotation of the second component may be permitted by providing mating cylindrical surfaces between the components, where are typically known as sleeve bearings, as one of the two components is typically sleeved with a material that provides low friction rotation between the moving components.
Alternatively, a widely used configuration to permit rotation between the components is in the form of a set of rolling elements that are positioned between the cylindrical surface of one component and the cylindrical surface of the second component. The rolling element may be balls, needles, cylinders or cylinders with spherical outer peripheries, also known as spherical rollers. A single row of rolling elements may be used, or two or more rows may be used in a spaced apart configuration. The rolling elements may be placed in adjoining relationship on the outer periphery of the inner element and on the inner periphery of the outer element. Alternatively, the rolling elements may be positioned in a spaced apart relationship, separated from each other by a separator in the form of a retainer or cage. The rolling elements and the inner element, ring or race and the outer element, ring or race form a rolling element bearing.
Separators or bearing retainers serve to separate adjacent rolling elements and to generally direct the rolling elements as they roll in the bearing races of the bearing inner ring and the bearing outer ring. Typically, the separators are supported by the rolling elements and float between the inner ring and the outer ring of the bearing.
Lubricants are used to provide lubrication of the bearing race surfaces and the rolling element surfaces. The lubrication of these surfaces greatly reduces friction and extends the life of the bearing. The lubrication typically is from natural or synthetic oil. The oil may be suspended in grease. The grease may move away from the path of the rolling elements during bearing use. This grease and the lubricating oil that is suspending in the grease are available for replenishment as the oil is consumed by the bearing.
The grease that tends to move away from the path of the rolling elements during use tends to move out to the sides and outer periphery of the bearing during operation due to centrifugal forces. This grease may not readily return to lubricate the bearing races when needed. Further this grease on the peripheries of the bearing may be washed out of the bearing during extremely wet and dry ambient operating conditions. These factors lead to either premature bearing failure or increased maintenance costs included more frequent lubrication of the bearings.
Separators may be made by any suitable process and be made of any suitable material. Typically, separators are made from two pieces stamped metal, formed to conform to the rolling elements and riveted together. Alternatively, separators may be machined from a metal, for example brass, or be molded from a polymer or a composite.
Metal separators require expensive tooling and equipment, much of which may be dedicated to a particular separator size. Further, the riveting of the stamped metal separators may result in missing rivets, contamination or other manufacturing issues. The stamped metal separators may not provide adequate rolling element guidance which may result in noise or other quality issues.
Alternatively, the separator may be made from a polymer. The polymer cage can closely conform to the rolling elements and be positioned radially by the rolling elements.
Alternatively, the inner ring may include lands that extend radially outwardly from the outer diameter of the inner ring. The separator may be positioned or supported radially by the lands of the inner ring.
The separator straddles both lands on the inner of a ring and typically does not have a lot of clearance between the ID of the cage and the lands of the inner ring. Supporting the separator by the lands may make it difficult for the lubrication to pass between the separator and the lands to proper lubricate the bearing raceways.
The present invention is directed to alleviate at least some of these problems with the prior art.